There are times when you’d like to have a certain type of post appear in a widget for use in your sidebar or (in some themes) your header or footer.
I used this to display a random senryu on each page, but it will work equally well for any group of reasonably small posts.
There is the option to include the title of the post, the title of the widget, both titles, or neither.
If you want you can add a bunch of widgets, each showing up to five random posts from a different category.

Random One Cat Widget

This Widget shows up to five random posts from a given category

bmsterling

This plugin retrieves one or more random post/page or both of them from your WordPress installation 
 Arguments: 
 from (string) 
 – show only posts, or pages, or both 
 – possible values: post | page 
 numberposts (integer) 
 – number of posts/pages to return 
 categories (integers, separated by commas) 
 – limits returned posts to posts filed under categories found in arguments 
 exclude (integers, separated by commas) 
 – limits returned posts to posts NOT filed under categories found in arguments
<pre><code>Sample Code:
 <?php
 $myposts = contentmixx( 'from=post&numberposts=2&categories=8' );
 foreach( $myposts as $post ) {
 setup_postdata( $post ); 
 ?>
 <div class="sideBarPost">
 <h3><a href="<?php the_permalink() ?>"><?php the_title() ?></a></h3>
 <?php the_excerpt(); ?>
 <a href="<?php the_permalink() ?>">Read More...</a>
 </div>
 <?php
 }
 ?>


 <?php
 $results = contentmixx('numberposts=3');
 foreach($results as $post) :
 setup_postdata($post);
 ?>
 <h2><a href="<?php the_permalink(); ?>" id="post-<?php the_ID(); ?>"><?php the_title(); ?></a></h2>
 <?php the_content(); ?>
 <?php endforeach; ?>
</code></pre>
Please submit any bugs or suggested improvements to <a href="https://github.com/bmsterling/Content-Mixx/issues" rel="nofollow ugc">https://github.com/bmsterling/Content-Mixx/issues</a>
Need this plugin customized or need a plugin created, contact me via my contact form at <a href="http://kenzomedia.com" rel="nofollow ugc">http://kenzomedia.com</a>
Also available through twitter, @bmsterling
<h3>Credits</h3>
Copyright 2007 Benjamin Sterling (http://benjaminsterling.com)
This program is free software; you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation; either version 2 of the License, or 
(at your option) any later version.
This program is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details: 
http://www.gnu.org/licenses/gpl.txt

Content Mixx

This plugin retrieves one or more random post/page or both of them from your WordPress installation

Random One Cat Widget vs Content Mixx